Fix non-Baker build.

rMR is defined only for Baker read barriers. Replace the
entire introspection marking entrypoint with "bkpt" for
other configs so that we do not use rMR if unavailable.

Test: m ART_USE_READ_BARRIER=false
Bug: 36141117
Change-Id: I12e856a7f0841d342477d1dcbd4f00652ee11efa
2 files changed